Snape is still working for Dumbledore in book 6

[Eddie]

No: HPFGUIDX 159474

> Alice:
> 
> Maybe this has been brought up, but I am sure Snape is
> working under cover for Dumbledore

Eddie:
Welcome to the group, Alice!

Variations of your very intelligent theory have made the rounds here,
but they were all pretty much squashed when Rowling said that
Dumbledore is dead and "won't pull a Gandalf."  That is, come back
from the dead as the wizard Gandalf did in Lord of the Rings.

See the messages that start around here:
http://groups.yahoo.com/group/HPforGrownups/message/156412

Eddie